Impulse actuated electromagnetic relay with time delay



' um. 27, 1948 "H. GQMILLER 2,434,948

' IMPULSE ACTUAL 1D ELECTROMAGNETIC RELAY WITH TIME DELAY J Filed Jan.27, 1944 Puss Sauna-'34 r u uwtzvroa C v HORACE 6. mai

Patented Jan. '27, 1948 IMPULSE AO'I'UATED. ELECTROMAGNETIC RELAYWITH'TIME DELAY Horace G. Miller, Belleville, N. .L, assignor to FederalTelephone and Radio Corporation,

New York. N. Y., a corporation of Delaware Application January 27, 1944,Serial No. 519,927 9 Claims. (01. 175-320) The present invention relatesto apparatus oi the type suitable for regulating the operation ofelectrically controlled circuit breaking devices.

devices being receptive erated at a diflerent source.

It is frequently desirable to provide means for I automaticallymaintaining an electrically controlled circuit breaking device such as arelay in one of its control positions after the flow of energy throughthe device has ceased. It is also desirable to cause the device toremain in this control position for the same predetermined period oftime following the initial reception of each of the various intervals ofenergization, without regard, within certain limits, to the duration ofthe intervals or the time that elapses between them.

It is accordingly the principal object of the present invention toprovide a simple and inexpensive circuit arrangement for carrying outthe above aims.

It is a further object oi. the invention to provide additional means inan arrangement of the above type that will permit the position of thecircuit breaking device to be altered before expiration of the saidpredetermined period of time and without regard to the status of theautomatic maintaining means. 7 It is a still further object of theinvention to provide an improved form 01' time-delay system for acircuit breaking device, the period. of delay being determined by thetime constant of a resistance-condenser combination.

It is an additional object of the invention to provide a holding circuitfor a relay, this circuit being responsive to an initiating input pulseof relatively narrow width, for holding the relay in closed position foran interval of time that is longer in duration than that of theinitiating input pulse.

It is a further object of the invention to provide a single time-delaycircuit eflective to control the operation of a plurality ofcircuit-break ing devices receptive'to pulses generated at sepa-- ratesource and designed to control separat loads.

It is a still further object of the invention to provide means forderiving pulses of equal width from pulses of unequal width.

Other objects and advantages will be apparent from the followingdetailed description of pre- Fig. 1 of the drawing accordingly shows twoseparate control circuits each including a separate circuit-breakingdevice, these circuits being energized by pulses generated at diiierentsources. A single time-delay circuit is so incorporated with thesecontrol circuits as to provide a delay interval for each, this intervalbeing of equal duration to thereby cause all of the control circuits toremain energized for substantially identical periods of time.

Although any number of control circuits may be incorporated with thesingle time-delay circuit as will later become apparent, only two havebeen illustrated, and the operation of the invention will be describedin connection with but one.

In Fig. 1 is shown three triodes V1, V2 and V3, the grids of which arerespectively connected to three pulse sources "A, B and "C." Thesesources produce pulses of widths t1 t4 and ts, as indicated, which maybe equal or unequal. The anodes oi triodes V1, V9 and V; are connectedto a ource of power 3 through the coils of three relays I, 5 and 4'respectively. Relays 4 and l are each provided with two pairs ofnormally open contacts 8, 1 and 6', 1' respectively. Relay 5 is providedwith a pair of normally closed contacts 8. In a conventional manner eachof these pairs includes a stationary contact and a; movable contact asillustrated.

A resistor R1 is connected between the anode terminal or the coil ofrelay 4 and normally open contacts 6. Another resistor R3 is connectedin a similar manner between the anode terminal of the coil of relay land normally open contacts 6'. Contacts 6 and 6' are joined as shown ,tonormally closed contacts 8. Contacts 8 are in turn connected to oneplate of a condenser C, the other plate of the condenser being grounded.

Shunted across condenser C is a further resistor R2. In parallel with Cand R: is a manually operable switch S. Normally open contact I and Irespectively control the flow of power from sources iii and It to loadsii and H.

The invention will now be described in connection with one of thecontrol circuits shown in Fig. 1. Since the principle or operation ofeach of these circuits is the same, the one including triode V1 has beenselected. Obviously, however, the one including triode V3 might asreadily have been chosen. In the following description, switch S iassumed to be open.

When a pulse from source A of duration t1 is applied to the grid oftriode V1 (both V1 and V2 being biased to or beyond cut-off) the tubebecomes conductive and current will flow through the coil of relay 4.Contacts 6 and 1 will now close.

As soon as contacts 6 close, a circuit will be to pulses of energy gen--established through source or power 8. coil 4, resistor R1. normallyclosed contacts 8 and to ground through condenser C. This will chargecondenser C for a period which will be designated as is. During thisperiod ta that C is chi-13 118 through R1, current flowing through thecoil of relay 4 maintains contacts 6 and 1 closed.

When C becomes fully charged (the time constant t: required for suchcharging being dependent on the values oi. R1 and C in a manner known inthe art), the current flow through the coil of relay 4 will cease, andcontacts 6 and 1 will open. It will be noted that the energy representedby the pulse from source A may or may not be applied to the grid oftriode V1 during the entire period lie that C is charging, it beingimmaterial whether the initiating energy continues or not after suchtime as the relay 4 is locked-in by establishment of a circuit throughR1 as above described. However, the interval t1 preferably should notexceed the time constant 1.: of RiC, the values of R1 and C beingselected with this condition in mind.

Resistor R2 is chosen to be of a considerably higher value than R1 so asnot to aiiect to any appreciable degree the charging of C through R1 aspreviously described. The purpose 01' R2 is to discharge condenser Cupon breaking of the circuit through resistor R1. and to thereby restorethe system in preparation for another cycle of operation. If the timerequired for C to completely discharge through R: after contacts 6 openbe designated as ts, then it will be seen that the sum of t: and is canequal but not exceed the time between successive pulses from source A.

The loads H and H respectively controlled by contacts I and I may be ofany standard type, such as for example stepping relays. Also thecontacts 1 and I may, if desired, control the operation of pulsegenerating devices for producing pulses having a width corresponding tothe intervals during which contacts i and I are closed. Many othercontrol applications will also be readily apparent to those skilled inthe art.

The above cycle of operation has assumed that switch S is open (or thatthe system is selfclearing), and that triode V2 is non-conductive. If,however, switch S be closed (making the system remote-clearing"),elements C and R2 will be short-circuited, and a closing of contacts 6and l as above described would normally result in the contacts remainingin such position indefinitely.

However, if a pulse from source B of some duration such at it is nowapplied to the grid of triode V2, the latter becomes conductive toenergize the coil of relay 5. Contacts 8 now open, breaking the circuitfrom the coil of relay 4 through R1 to ground by way of switch S.Contacts 6 and I now open due to the deenergization of the coil. It willbe seen that a pulse from source B may be received by triode V2 at anytime subsequent to the arrival of a pulse from source A on the grid oftriode V1. It will also be seen that the remote-clearing action of thesystem dominates the self-clearing or automatic action. This is truebecause opening of contacts 8 as a result of the energization of relay 5by the pulse from source B clears the holding circuit and opens contacts6 and I regardless of whether switch S is open or closed. Also theduration t; of the pulse from source B may be immaterial, if the onlyrequirement is that the triode V2 be conductive for a sufficient time topermit contacts 8 to open. However it will be clear that t4 must not beof such length as to interfere with the chargin of condenser C upon thereception of the next pulse by triode V1 from source "A."

It will be obvious that the separate control circuit including triode V:and relay 4' operates in a manner similar to that described above forthe triode V1 and relay 4. Resistor Rs may have a value such that thetime constant RcC equals R1C, or else it may have any other valuedesired so that contacts 'I' will remain closed for longer or shorterintervals than contacts 1.

However, it is emphasized that, in order for all of the intervals duringwhich contacts 1' are closed to be or equal duration. and in order forall of the intervals during which contacts I be closed to be also ofequal duration, the pulses from sources "A and 0'' must not arrivesimultaneously, and furthermore successive pulses, whether from the sameor from diflerent sources, must be spaced apart a suiiicient distance toallow for theiull discharging of condenser C.

It will be obvious that if desired additional circuits including relays4' and triodes V: may be added in parallel relation with the one shown.

In Fig. 2 is illustrated a circuit incorporating a different type ofcondenser discharging means from that shown in Fig. 1. In thisarrangement an additional stationary contact 6a is associated withcontacts 6, so that condenser C is normally short-circuited when relay 4is deenergized. When current flows through the coil of relay 4 as aresult of the reception of a pulse from source A, condenser C willcharge in the manner previously described. When the how oi currentthrough the relay coil ceases due to the attaining by C of its fullcharge through R1, contacts 6 will open. This opening of contacts 8 willshort-circuit condenser C through contact Ba thereby discharging thecondenser to ground. Thus the system is conditioned for another cycle ofoperation. It will be noted that in the arrangement as shown in Fig. 2the separate discharging resistor R2 of Fig. 1 is not required. However,this arrangement of Fig. 2 is suitable for only one relay 4.

From the above it will be seen that the present disclosure includesnumerous features. Means are provided whereby a circuit breaking devicemay be held in closed position for a predetermined period of time thatexceeds in duration that of any of the initiating pulses. This samepredetermined holding period is maintained even though the width ofsucceeding received pulses may vary to a considerable degree. If it isdesired to maintain the closed position of the device until such time asa clearing pulse is received, this may be accomplished through the actof closing a selector switch as shown in Fig. 1. In addition the systemprovides means whereby means such as a clearing pulse will be effectiveto deenergize the system regardless of whether the selector switch hasbeen closed or not, and.

also without regard to the status at that time of the automatic clearingmeans.

While I have described above the principles of my invention inconnection with specific circuit arrangements, it is to be clearlyunderstood that this description is made only by way of example, and notas a limitation on the scope of my invention as set forth in the objects0! my invention and in the accompanying claims.

I claim:

1. In an electrical circuit including an energy source, anelectro-responsive mechanism anda source of power, the combination of anormally inoperative control element in circuit relation with saidsource of power and said electro-responsive mechanism, means responsiveto the initial reception of energy from said source, said energy beingof a certain duration to render said element operative to energize saidelectro-responsive mechanism, a resistance-condenser combination havinga time constant greater than the duration of said reception of energysaid combination being serially connected across said source, and meansunder control of said resistance-condenser combination, whereby saidmechanism is maintained energized for a predetermined time over acircuit independent of said control element.

2. An electrical circuit. according to claim 1 in which theelectro-responsive mechanism is energized by current flow to charge saidcondenser.

3. An electrical circuit according to claim 1, further comprising meansfor discharging the condenser of said resistance-condenser combinationafter deenergization of said electro-responsive mechanism following theenergization thereof, and prior to the next succeeding reception ofenergy by said normally inoperative control element, said dischargingmeans being connected in parallel with said condenser.

4. In an electrical circuit including a normally open relay and a sourceof power, a normally nonconductive element in series with said source ofpower and with the coil of said relay, a, first source of pulse energy,means responsive to the initial reception of a pulse of energy of acertain duration from said first source by said element to render saidelement conductive and thereby close said relay, a time-delay circuitconnected in operative relation with the relay coil over a pathindependent of the normally nonconductive element and having apredetermined delay interval greater than the duration of the pulse ofenergy received by said element, and means responsive to the closing 01'said relay to initiate the operation of said time-delay circuit,

whereby said relay will open at the expiration of said delay interval.

5. An electrical circuit according to claim 4, further comprising asecond normally non-conductive element, and means responsive to thereception of energy by said second element during the said time-delayinterval to return said relay to open position irrespective of theelectrical status or the said time-delay circuit at the time energy isreceived by said second element.

6. In anelectrical. circuit including a pair of relays and a source ofcurrent. the combination of a pair of normally non-conductive elements.

- two series circuits, each circuit including the source of current, thecoil of one of the said relays, and one of the non-conductive elements,

' respectively, means for rendering one of said elesive mechanism asource of successive pulses of a certain duration t1 for controlling theclosing of said eectro-responsive mechanism, a condenser, meansresponsive to the initial reception of one of said pulses and connectedto said electroresponsive mechanism to initiate the charging of saidcondenser, means whereby the latter maintains the said mechanism closedduring a certain charginginterval t2, and a circuit rendered operativeby the opening of said mechanism following the closing thereof fordischarging said condenser during a third interval t3, wherein t2 tn andthe sum of is and ts is equal to'or less than the elap ed time betweenthe beginnings of suecessive pulses.

8. In combination, a source or current, an elecrically-controllednormally open circuitbreaking device connected to said current source, acircuit including a normally non-conductive element connected to saiddevice, an energy source for energizing said element, means responsiveto the initial reception of said energy, said energy being of a certainduration, to close said circuit-breaking device, a time-delay circuitserially connected with said current source having a predetermined delayinterval. means re sponsive to the initial reception or energy by saidelement to initiate the energization oisaid timede'ay circuit, saidpredetermined delay interval exceeding in duration the time during whichen ergy is received by said element, whereby said time delay circuitwill open at the expiration oi said predetermined delay interval.

9. In an electrical circuit including a plurality of electro-responsivemechanisms, a source of power, a source of energy, a plurality oinormally non-conductive,elements, each of said normally non-conductiveelements being respectively connected in series with one or saidelectro-respom sive mechanisms and said source of power, meansresponsive to the initial reception oi said energy by one of saidelements/to render said clement conductive and thereby energize theelectro-re sponsive mechanism in series therewith said energy being oi acertain duration. a plurality oi resistance condenser and derivingcharging cur= rent from said power source combinations having a commoncondenser. the resistances of each of said combinations beingrespectively associated with respective non-conductive elements. each ofsaid resistance-condenser combinations having a time constant greaterthan the dim. tion of reception of energy by the normally nonconductiveelement associated therewith, and means responsive to the energizationof one or said electro-responsive mechanisms to initiate the charging ofsaid condenser whereby said last mentioned electro-responsive mechanismwill be de-energized when said condenser is fully charged.

HORACE G. MILLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2.165.048 Gilliksen July 4, 19392,032,514 Swart Mar. 8, 1936 2,147,468 Stoddard ..'Feb. 14. 19392,221,569 Berkey et a1. Nov. 12. 1920 2,282,182 Gilliksen May 5. 19421,909,471 Kelly May 16, 1933 2,008,413 Dawson July 16, 1935

